Production of explosives



June 23, 1959 i s rr 2,891,563

PRODUCTION OF'EXPLOSIVES Filed Au 11, 1953 2 Sheets-Sheet 1 FIG. 2.

I N VE N TO R Jfennei'h Ashbmpke mith,

W WJ ATTORN E Y5 June 23, 1959 K. A. SMITH 2,391,563

PRODUCTION 0 EXPLOSIVES Filed Aug. '11, 1953 2 Sheets-Shh 2 I 52 54 42as I8 49 FIG. 5

INVENTOR.

Kenneth Aabb kesmah,

ATTORNEYS.

United States Patent 2,891,563 PRODUCTION or EXPLOSIVES KennethAshbrooke Smith, West Kilbride, Scotland, assignor t0 Imperial ChemicalIndustries Limited, a corporation of Great Britain Application August11, 1953, Serial No. 373,493

Claims priority, application Great Britain September 19, 1952 9 Claims.(Cl. 137-1) The present invention relates to improvements in or relatingto the transporting of liquid explosive nitric esters of polyhydricalcohols for example nitroglyc'erine, nitropolyglycerine, ethyleneglycol dinitrate and diethylene glycol dinitrate.

It is frequently necessary to transport these liquid ex-' plosive nitricesters for long distances, as for example, in the production ofexplosive compositions containing liquid explosive nitric esters. Thehazard in carryng out transportation by a pipeline is that if anexplosion is initiated at any point therein it is likely to betransmitted along the whole length of the pipe. Various methods havebeen adopted in attempts to overcome this hazard,

for example, nitroglycerine or ethylene glycol dinitrate,

or a mixture of these two esters has been transported as an emulsionwith Water. This method is satisfactory, but

involves the additional steps of making and breaking an. emulsion andthese additional steps are not without hazard. Anothermethod which hasbeen adopted is to provide in the pipeline a number of syphoningarrangements of differing capacities so that at no time is there acontinuous mass of explosive liquid throughout the system. This methodalso suffers from a number of disadvantages.

From general and fundamental principles underlying and governing thebehaviour of explosives it was thought that a tube carrying a liquidexplosive nitric ester should have a maximum diameter below whichpropagation of detonation becomes impossible however intense the sourceof detonation. It was experimentally ascertained that a tube carrying aliquid explosive nitric ester has such a maximum diameter and that it isabout 0.1 inch and that the actual upper limit depends inter alia on thenumber of narrow bored tubes used to divide the path of flow of theliquid nitric ester, the material of the tubes and the nature of thesurrounding material for the tubes, e.g. whether the tubes aresurrounded by air or are immersed in a solid medium. To achieve adequaterate of flow it was clear that the number of narrow bored tubes used inany one set to form a multi-divided path for the liquid ester wouldusually have to be at least 10. Also it Was clear that to prevent flashover it would be necessary in practice for the set of narrow bored tubesto be at least 3 feet in length. Furthermore as it was known that toapply a pressure of more than 20 times an existing pressure on a bulk ofliquid explosive nitric ester may produce an explosion in said bulk dueto adiabatic compression of occluded air bubbles in the nitric ester(Detonation of Liquid Explosives by Impact, Nature, vol. 157, p. 105,Jan. 26, 1946. F. P. Bowden, M. F. R. Mulcahy, R. G. Vines, A. Yoife) itWas clear that the forcing pressure to be applied to force the liquidexplosive nitric ester through any one set of tubes each of diameter notgreater than 0.1 inch has to be less than 20 times the pressure on theester before the application of this forcing pressure.

According to the present invention the method of transporting a liquidexplosive nitric ester comprises forcing said liquid under a forcingpressure less than 20 times "ice the pressure on the ester before theapplication of this forcing pressure through at least one set of tubesof pressure resisting material not aifected by said liquid explosive,arranged to form a multi-divided path for the ester and each of at least3 feet in length and internal diameter not greater than 0.1 inch.

The phrase pressure resisting materia includes steel but preferably thematerial for the tubes is based on natural or synthetic rubbers orthermoplastic resins such as polyethylene, polyvinyl chloride, syntheticlinear polymers and the like.

The number of small bore tubes required in a section of the pipelinewill be determined by the required rate of delivery and pressure of theexplosive ester and may, for example, vary from 10 to 400.

The bore of the tubes may in some instancesbe considerably less than 0.1inch. Furthermore, since tubes 7 made of materials like rubber, neopreneor polyethylene may undergo an increase in bore while in use because ofthe pressure necessary to force the liquid therethrough, it is preferredto have a bore of not more than 0.09 inch. The thickness of the tubesshould be sufficient to enable them to withstand the working pressureand will, of course, vary according to the properties of the materialfrom which the tubes are made.

If desired any set of small bore tubes may be enclosed in steel tubingor other conduit material while it'passes through obstructions, forexample, such as blast walls. Sometimes it is desirable to fill theconduit with water or other non-flammable fluid to prevent the passageof a .flame or other disturbance external to the trap causingpropagation of an explosion through the conduit. The use of enclosingconduits is not, however, desirable where the small bore tubes carry theexplosive liquid across an open space.

The small bore tubes may be of any convenient length, for example, fromat least 3 feet up to feet or longer. Thus they may be of the lengthrequired to carry the explosive liquid through the blast wall or moundwhich is positioned outside the building to or from which it is beingtransported or they may be longer. The small bore tubes may also be usedto replace the section of pipeline passing through the partition betweentwo compartments in the same building or in any otherconvenient'position where it is desired to stop propagation of anexplosion; Thus, for example, their use is highly advantageous at theend of a pipeline for feeding the explosive ester into a mixer for thecontinuous mixing of explosive compositions and for this purpose thesmall bore tubes can be made of differing lengths so that the explosiveliquid can enter the mixer at various points.

The pressure used to force the explosive ester through the tubes willdepend on the length of the small bore tubes through which the liquidexplosive ester has to be passed and on the pressure which the tubingwill withstand without rupture. The working pressure may be obtained inone stage or a number of stages. Care must be taken, however, aspreviously stated that the compression ratio for any stage is alwaysless than 20 to 1 so as to prevent the possibility of an explosion b-yadiabatic compression of air contained in the explosive ester. Theliquid explosive nitric ester which is forced through a set of narrowbore tubes may have additional pressure applied to the liquid by meansof a pump which may be for example a multi-cylinder gas operateddiaphragm pump as disclosed in Patent No. 2,821,930 in order to forcethe liquid through a further length of a set of narrow bored tubes. Theinlets and outlets for the pump may be in the formof a multiplicity ofsmall bor'e tubes if desired. 1 i

A further advantage of the invention is that if a pulsating supply ofliquid explosive nitric ester is fed for exam- 3 pie, from a pump, tothe small bore tubes of any one set of elastically deformable materialthe pulsations are evened out and a continuous flow of ester is given atthe exit end of the tubes.

In the following table the first part shows examples of the use oftubing suitable for the practice of the present invention and the secondpart shows the use of unsuitable tubing. The tubes were filled with anitrated mixture of glycerol and ethylene glycol (ratio 80:20) andexplosions were initiated outside the tubes at one end to determineWhether the explosions would be propagated beyond the other end of thetubes.

through a set of 30 neoprene tubes 16, each one having an internal boreof 0.09 in. and each being 75 ft. long. These neoprene tubes 16 lead theliquid explosive nitric ester mixture directly into a mixing machine 17.The delivery of the liquid explosive nitric ester from tubes 16 is inthe form of droplets at a uniform rate of 4 lbs/minute.

The pressure of 3 atmospheres which is applied to the liquid explosivemixture in tank 3 is suflicient to force the liquid into the diaphragmportion 18 of the gas perated diaphragm metering pump 15.

Referring to Fig. 2 the set of neoprene tubes 4- en- Wall Length NumberPropaga- Materlal thickness (feet) of tubes Confined or not tiou(inches) Polyethylene s 0.060 0.060 6 D0 0. 0.03 6 l 0. l9 0. 06 6 1 N00.070 0.08 6 14 Yes: in 1% steel No.

tubing. 0.085 0406 3 14 No No. 0.085 0.06 3 14 Yes: in 2% pipe No. 0.070 0.08 4 19 Yes: in 1% tube No. 0.070 0.08 4 Yes: in water No.

filled 1% steel tube. 0. 085 0.06 4 16 Yes: in 1% steel N0.

tube. 0.080 0.035 3 4 N0 NO. 0.080 0 035 3 8 Yesrbin steel N0.

tn e. 0. 0625 0.0625 4 4 Yes: in steel No.

tubing. 0 091 0.035 4 9 Yes: in water No.

filled tube. 0.080 0 035 3 Q N0.

Steel 0.03 0.10 4 1 NO. Polyethylene 0. 125 0.06 6 4 Yes. Neoprene 0.105 0. 035 4 7 Yes. Rubber 0. 144 0. l0 4 1 Yes.

The invention is illustrated by the following example and with referenceto the diagrammatic drawing attached hereto in which Fig. 1 is aschematic view of a layout suitable for carrying out the method of theinvention for transporting a nitrated mixture of glycerol and ethyleneglycol (ratio 80:20) from a container in a nitroglycerine wash house toa mixing machine 300 ft. away into which the nitrated mixture is meteredand mixed with the other ingredients required for the production ofblasting explosive compositions, Fig. 2 is a crosssection on an enlargedscale of a set of narrow bored tubes enclosed in a wider tube, and Fig.3 is a partly cross-sectional and partly schematical view on an enlargedscale of a gas operated diaphragm metering pump of the kind disclosed inPatent No. 2,821,930.

A nitrated mixture of glycerol and ethylene glycol (ratio 80:20) iscontained in a tank 1 in a wash house. From tank 1 the nitrated mixtureflows under gravity through valve 2 to tank 3 wherein it is subjected toa pressure of 3 atmospheres and is thus forced through a set of 30neoprene tubes 4 each one having an internal bore of 0.09 in. and eachbeing ft. long. The set of tubes 4 pass through a protective mound 5.The portion of this set of tubes 4 which is within the mound 5 isenclosed in a polyethylene tube 6 of 1 /2 in. bore through which brineis circulated. The liquid explosive nitric ester then continues itstravel through a polyethylene tube 7 of A in. bore by Way of a couplingunit 8. The polyethylene tube 7 is underground and passes under smallprotective mounds 9 and 10 and then to a coupling unit 11 for connectionto another set of neoprene tubes 12 each one having an internal bore of0.09 in. and each being 25 ft. long. This set of tubes 12 passes througha protective mound 13. The portion of this set of tubes 12 which iswithin the mound 13 is enclosed in a polyethylene tube 14 of 1 /2 in.bore through which brine is circulated. This set of tubes 12 conductsthe liquid explosive nitric ester mixture directly into a gas operateddiaphragm metering pump 15 from which the liquid explosive nitric estermixture is pumped directly closed in a neoprene tube 6 is shown in crosssection on an enlarged scale.

Referring to Fig. 3 wherein the gas operated diaphragm metering pump 15is shown on an enlarged scale partly in cross-section and partlyschematically 19 is a gas distribution valve shown schematically whichcan rotate in a closely fitting housing (not shown) and is connected toa diaphragm portion 18 shown in vertical cross-section. The gasdistribution valve 19 comprises a rotatable cylinder one half of whichis so constructed as to permit the distribution of gas pressure and theother half is so constructed as to permit the release of gas pressure tothe atmosphere. The half which permits distribution of gas pressure isprovided with part circumferential grooves 20 and 21 and the other halfwhich permits release of gas pressure is provided with partcircumferential grooves 22 and 23. The close fit of'the housing roundthe rotatable cylinder in effect converts these circumferential grooves20, 21, 22 and 23 into ducts positioned and rotating Within the housing.The housing has six ducts 24, 25, 26, 27, 28 and 29. During a portion ofthe revolution of the distribution valve 19 groove 20 communicates withduct 24 and during another portion of its rotation with duct 26 and inone stage of rotation ducts 24 and 26 are in communication with eachother through groove 20, but this is of no significance. Similarlygroove 21 communicates with duct 27, groove 22 with duct 28 and groove23 with duct 25 or duct 29. Ducts 2S and 29 are never in communicationwith each other through groove 23 and axial duct 30 is always incommunication with groove 20 through ducts 31 and with groove 21 throughducts 32. Another axial duct 33 is always in communication with groove22 through ducts 34 and with groove 23 through ducts 35. The axial duct30 can be connected to a gas supply through a pipe 36 by way of areducing valve 37 which controls the gas pressure to be delivered to thegas distribution valve 19 to a pressure less than a predeterminedmaximum pressure which is to be greater than the pressure which is to beapplied to the liquid to be introduced into the diaphragm portion 18.duct 33 is open to the atmosphere.

The diaphragm portion 18 contains cavities 38, 39 and 40. Cavity 38 hasa diaphragm 41. Cavity 39 has a diaphragm 42 and cavity 40 has adiaphragm 43. Cavity 38 is connected by pipe 44 to ducts 26 and 29,cavity 39 is connected by pipe 45 by ducts 27 and 28 and cavity 40 isconnected by pipe 46 to ducts 24 and 25.

Liquid inlet 47 communicates with cavity 39 through ducts 48 and 49except when diaphragm 41 in cavity 38 seals ducts 48 and 49. Similarlythe liquid outlet 50 communicates with cavity 39 through ducts 51 and 52except when diaphragm 43 in cavity 40 seals 01f ducts 51 and 52. Ducts49 and 52 are at all times in communication. 53, 54 and 55 are surgepreventing ducts.

The capacity of the liquid collecting chamber 39 is 6 ml. and thecapacity of each of the valve chambers 38 and 40 is 1.5 ml. The speed ofrotation of the gas distribution valve 19 can be varied as desired. Aconvenient rotational speed is 30 revolutions per minute.

The metering pump as illustrated shows it in a position about tocommence the discharge of liquid. The liquid at the outlet 50 issubjected to a back pressure due to the small bore tubing in the path ofthe discharge liquid in accordance with the process of the invention.

As duct 26 is in communication with groove 20 and so with the air supplyand since duct 29 is sealed air pressure is applied to diaphragm 41sealing off ducts 48 and 49. Ducts 27 and 24 are sealed of1 from the airsupply and ducts 28 and 25 are open to the atmosphere through grooves 22and 23 and therefore there is no air pressure on diaphragms 42 and 43.The liquid collecting chamber 39 is full of liquid and the outlet valvediaphragm 43 is in position to permit communication between ducts 52 and51. After the gas distribution valve 19 has rotated slightly duct 27 isbrought into communication with groove 21 and duct 28 is sealed off. Airpressure is thus applied to diaphragm 42 which moves so as to force theliquid from chamber 39 through ducts 52 and 51 to the outlet 50. Furtherrotation of the gas distribution valve 19 leads to the opening of duct24 to air pressure and the sealing of duct 25 and thus to theapplication of air pressure to diaphragm 43 causing this diaphragm 43 tomove so as to force liquid from outlet valve chamber 40 through duct 51to the liquid outlet 50 and then to seal duct 52 from duct 51. Onfurther rotation of the gas distribution valve 19 duct 26 is sealed offand duct 29 is opened to the atmosphere thereby permitting liquid underpressure to move from liquid inlet 47 through duct 48 to move diaphragm41 to fill inlet valve chamber 38 and to communicate with duct 49. Assoon as duct 27 is sealed off and duct 28 opened to the atmosphere thisliquid pressure enables liquid to flow through the inlet valve chamber38 through duct 49 to fill the liquid collecting chamber 39 therebymoving diaphragm 42 to the position shown in the diagrammatic drawing.Further rotation of the gas distribution valve 19 seals duct 29 and sopermits gas pressure through duct 26 and pipe 44 to actuate diaphragm 41and to force liquid from inlet valve chamber 38 through the duct 48,back into the liquid inlet 47 and then to seal duct 49 from duct 48. Ina further stage of rotation of the gas distribution valve 19 this valveis again in a position shown in the drawing when there is a release ofpressure from diaphragm 43. Liquid from the outlet 50 subjected to aback pressure moves through duct 51 to fill outlet valve chamber 40moving diaphragm 43 to the position shown in the drawing and bringingduct 52 into communication with duct 51. A complete cycle has thus beenperformed and the net or algebraic total volume of liquid discharged inthis one cycle through the outlet 50 is the volume of the liquidcollecting chamber 39.

To avoid lubricating the contact faces between the ro- Axial 6, tatablegas distribution valve" 19 and its housing there is a clearance of twothousandths of an inch between these faces and so to prevent leakagebetween grooves 20, 21, 22 and 23 circumferential grooves (not shown)open to the atmosphere are provided between said grooves 20 and 21, 21and 22 and 22 and 23.

Should any one of the diaphragms 41, 42 or 43 burst, the pump will ceaseto deliver liquid and liquid will not reach the gas distribution valve19 through pipes 44, 45 or 46.

What I claim is:

1. In a method of transporting a liquid explosive nitric ester from onelocation to another through joining conduit means, the improvementswhereby the hazard of transmitting throughout the length of said conduitmeans, an explosion initiated at any point in said means is effectivelyeliminated, said improvements including the steps of (1) utilizingconduit means which comprise a set of tubes of pressure-resistantmaterial that is chemically inert to said liquid explosive nitric ester,said tubes being arranged to form a multi-divided path for said esterwith each of said tubes being at least three feet in length and havingan internal diameter not greater than 0.1 inch, and (2) transportingsaid liquid explosive nitric ester through said tubes from one locationto the other, by forcing said ester through said tubes under a forcingpressure which is less than 20 times the pressure on said ester prior tothe application of said forcing pressure, and said tubes being ofsuflicient internal diameter to permit passage therethrough of saidliquid explosive nitric ester under said forcing pressure.

2. A method as claimed in claim 1 wherein the pressure resistingmaterial is based on a material selected from the group consisting ofnatural rubber, synthetic rubber and thermoplastic resin.

3. A method as claimed in claim 1 wherein a set of tubes consists of 10to 400 tubes.

4. A method as claimed in claim 1 wherein the bore of each tube is notmore than 0.09 inch.

5. A method as claimed in claim 1 wherein a set of small bore tubes isenclosed in conduit material filled with non-flammable fluid.

6. In combination, a source of liquid explosive nitric ester, meansspaced from said source for receiving liquid explosive nitric ester fromsaid source, and conduit means for transporting said ester from saidsource to said receiving means, said conduit means comprising aplurality of tubes of pressure resistant material that is chemicallyinert to said ester, said tubes being arranged to form a multidividedpath for said ester, said tubes being of different lengths, each of saidtubes being at least three feet in length and having an internaldiameter not greater than 0.1 inch, and said tubes being of sufficientinternal diameter to permit passage therethrough of said liquidexplosive nitric ester under a forcing pressure which is less thantwenty times the pressure on said ester prior to the application of saidforcing pressure.

7. The combination of claim 6 including at least 10 tubes, said tubesbeing enclosed in a conduit permitting circulation of fluidtherethrough.

8. Means for transporting liquid explosive nitric ester from onelocation to another, said means comprising a conduit joining onelocation with the other, said conduit including a set of tubes ofpressure-resistant material that is chemically inert to said ester, saidtubes being arranged to form a multi-divided path for said ester, saidtubes being of different lengths, and each of said tubes being at leastthree feet in length and having an internal diameter not greater than0.1 inch, and said tubes being of sufiicient internal diameter to permitpassage therethrough of said liquid explosive nitric ester under aforcing pressure which is less than twenty times the pressure on saidester prior to the application of said forcing pressure.

9. In combination, a first building, a first protective Wall spaced fromsaid first building, a second building, a second protective wall spacedfrom said second build ing, said protective walls being interposedbetween said buildings, a multiplicity of narrow bore tubes of not lessthan three feet in length provided through each of said walls, fluidconduit means intermediate said walls and connected to said tubes ineach of said walls, a source of liquid explosive nitric ester in saidfirst building, means for connecting said source to said tubes in saidfirst wall, and means to connect said tubes in said second Wall to saidsecond house.

References Cited in the file of this patent UNITED STATES PATENTS JonesMay 9, 1933 Crowe Aug. 14, 1951 OTHER REFERENCES Fiat Final Report720-28, January 1936, German Techniques for Handling Acetylene inChemical Operations, by N. A. Copeland and Mt A. Youker, Joint Intel- 10ligence Objectives Agency; published by Ofiice of Military Govt. forGermany (U.S.), call No. "RP. 248 A 3c6, pages 64 and 66 inclusive.

